Originally created 09/16/99

Capsules



Health risks

A long-term study of more than 9,000 doctors found that those who were overweight at age 25 had a significantly increased risk of developing adult onset diabetes by age 50.

Advice about weight control as a means of preventing diabetes should be given to people in young adulthood as well as those who are middle-aged, Dr. Federick L. Brancati of Johns Hopkins reported in the Archives of Internal Medicine.

The hard cell

In a fascinating turnabout, researchers have found a way to convert specialized cells that usually trigger an immune response into cells that trigger cell death.

The research, done in mouse cells by scientists at the University of Texas Southwestern Medical Center in Dallas, might one day lead to treatment of diseases such as rheumatoid arthritis that stem from inappropriate responses by the body's immune system.

"What we did was to change the concept entirely," said Dr. Akira Takashima, a Texas dermatology professor. "We tried to convert dendritic cells into cells that deliver death signals instead of activation signals."

Dendritic cells are a type of white blood cell that signal other cells, called T lymphocytes, to multiply at a faster rate to mount an attack on an outside invader. When the dendritic cells send their signals inappropriately, it can do far more harm than good.

The next step, Dr. Takashima said, will be to see if the researchers can use what they've learned from mouse cells to create a technology that can be used in trials with human patients.

Mental breakdown

There may be a mental link to broken hips: Older women who are down in the dumps are more likely to break a hip, according to a Norwegian study of 18,500 women.

Women who were lonely, depressed or mentally distressed were twice as likely to break a hip as women who did not have these problems, said Dr. Lisa Forsen of the National Institute of Public Health in Oslo.

Mentally distressed women have two strikes against them: Increased stress hormones can weaken bones, and these women are more likely to engage in risky behaviors, such as smoking and poor diet, Dr. Forsen reported in the Journal of Epidemiology and Community Health.

Landslide danger

More than 2,200 people died in the 1998 tsunami in Papua New Guinea, but they actually lost their lives because of a landslide.

A new study suggests the tsunami was triggered not by the magnitude-7.1 earthquake that struck nearby, but by an underwater landslide the quake set off.

Two research groups went to northern Papua New Guinea this year, probing the sea floor for clues to what caused the 30-foot-high tsunami of July 17, 1998. Both groups found that a huge chunk of the seabed had collapsed some 15 miles offshore from a lagoon called Sissano.

David Tappin of the British Geological Survey and colleagues published their results this summer in the scientific newsletter Eos.

The landslide theory could explain why it took longer than expected for the tsunami to reach the coast; it took several minutes for the quake to trigger the landslide, which in turn caused the tsunami. It could also explain why the tsunami was so big even though the earthquake wasn't, the scientists write.

The work also suggests that landslides could create tsunamis in areas not thought to be at high risk, such as Southern California.

Rising ranges

Geologists may have explained one of Earth's most complicated mysteries -- how the rise of mountain ranges influences global climate.

At first, it seems odd that the Himalayas or Rockies could change the climate of Bangladesh or Bermuda. But for the last decade, many scientists have argued that rising ranges could cool the entire planet.

The theory holds that rising mountains provide more rock that can chemically react with carbon dioxide in the atmosphere, sucking the heat-trapping gas from the air. Supporters say this idea could explain why Earth started cooling about 60 million years ago, when the Himalayas began to rise to great heights.

The cooling, scientists think, would cause glaciers to form and more storms to occur. Both of these would increase erosion, making mountains taller as valleys are cut deeper.

But the Himalayas aren't unbearably high, and the planet isn't unbearably cold. That's because a cooler climate didn't necessarily cause more erosion, scientists from the Massachusetts Institute of Technology reported this month in Nature. Geologist Kelin Whipple and colleagues reached that conclusion by studying mountain streams and their response to changing climate.

The Himalayas probably helped cool the planet only once, millions of years ago, scientists say.